THOUSAND OAKS, CA — A decorated military veteran possibly suffering post-traumatic stress disorder opened fire and killed 12 people at a popular country-music bar that attracted area college students.

On Wednesday night, November 7, Ian David Long, 28, dressed in black and armed with a legally purchased Glock 21 .45-caliber pistol with an extended magazine, drove his mom’s car to the Borderline Bar & Grill.

Without saying a word, Long burst into the venue at about 11:20 P.M. and began shooting, first at a bouncer and then at a cashier.

“He just pulled out a gun and shot my friend that was working the front desk,” said 21-year-old Holden Harrah.

"I started hearing these big pops. Pop, pop, pop. There was probably three or four, I hit the ground," recalled eyewitness John Hedge.

Several survivors thought Long also detonated what appeared to be smoke bombs.

While some took shelter under pool tables, in bathrooms, and around the bar, others smashed windows to escape. “All I could think about was how helpless I was,” said Borderline regular Matthew Wennerstrom.

Six minutes after the attack began, police arrived on the scene. Sergeant Ron Helus, a 29-year vet of the Ventura County Sheriff’s Office, was first to run into the bar to stop the threat. He was shot and later died of his wounds.

One victim of the shooting who has been identified is Alaina Housley, the niece of TV actress Tamera Mowry-Housley, star of Sister, Sister; The Real; and Tia & Tamera; and her husband, Fox News correspondent Adam Housely.

Mowry-Housley went to Twitter to search for any news of her missing niece and discovered that the college student was the only one from a handful of girlfriends who went line dancing not accounted for after the shooting. She eventually discovered the Pepperdine freshman had been killed in the attack.

"Alaina was an incredible young woman with so much life ahead of her, and we are devastated that her life was cut short in this manner. We thank everyone for your prayers and ask for privacy at this time," Mowry-Housley said in a joint statement with her husband.

Long is believed to have died from a self-inflicted gunshot.

Local police, the FBI, and other government agencies are now looking into Long’s history and trying to determine his motive for going on the rampage.

Defense Department records show Long served almost five years as an infantry machine gunner in the Marine Corps, including a stint in Afghanistan between November 2010 and June 2011. He also spent time as an instructor in Okinawa, Japan, before heading to Southern California to study sports medicine.

In March 2017, Long wrote on a special forces online forum called ShadowSpear: “I was honorably discharged in 2013. I am graduating with a B.S. in Athletic Training in two months. I found out a little too late that just wasn't the job for me. Maybe the ego got the better of me but it took only one time for a 19 year old D-2 athlete to talk down to me and tell me how to do my job that I realized this wasn't the career I wanted to head.”

Around a month following the confession, in April 2017, Sheriff Dean said mental-health specialists investigated Long after police were called to his Newbury Park home because he was irate and acting irrationally, but they determined he could not be detained under California law.

According to one of Long’s neighbors, the vet had PTSD and would cause problems at the house he shared with his mom. “She’s a very sweet woman, but she had a lot of problems with the son,” said Richard Berge, 77. “I just know he tore the house up.”

Long's cousin, AJ Schramm, told CBS News that the killer’s mother was “venting” over her son’s behavior when she recently attended a family wedding.

Police said besides the call in spring, they only had limited contact with the killer — he was the victim in a 2015 bar fight and once had a minor traffic accident — and Long left few clues to his motivation for committing the murders.

Tragically, some of Long’s victims may have also been at the Route 91 Harvest Festival in Las Vegas last year when 64-year-old Stephen Paddock rained down gunfire on thousands of concertgoers, killing 58.

“There are a few people we can’t get ahold of, but in these situations people usually turn off their phones to be safe, so I’m not going to get too worried. A lot of my friends survived Route 91,” Carl Edgar, 24, said shortly after the bar shooting. “If they survived that, they will survive this.”

Sheriff Dean said even a place as quiet as Thousand Oaks can become a target. “It doesn’t matter how safe your community is, it doesn’t matter how low your crime rate is — there are people who just don’t think properly everywhere, I don’t care where you are, and they commit horrific acts like this,” he said. “There’s no way to process. There’s no way to make sense out of the senseless.”

After ascending to the peak position of the Branch Davidians in 1990, Vernon Howell legally changed his name to David Koresh. Court documents indicate the name change was officially “for publicity and business purposes.”